[SCOI2005]王室联邦

分块基本没有限制
所以每次大于等于b就分一块

# include <bits/stdc++.h>
# define RG register
# define IL inline
# define Fill(a, b) memset(a, b, sizeof(a))
using namespace std;
typedef long long ll;
const int _(2e3 + 10);

IL ll Read(){
    char c = '%'; ll x = 0, z = 1;
    for(; c > '9' || c < '0'; c = getchar()) if(c == '-') z = -1;
    for(; c >= '0' && c <= '9'; c = getchar()) x = x * 10 + c - '0';
    return x * z;
}

int b, n, fst[_], num, nxt[_], to[_], cnt, bel[_], S[_], rt[_];

IL void Add(RG int u, RG int v){  to[cnt] = v; nxt[cnt] = fst[u]; fst[u] = cnt++;  }

IL void Dfs(RG int u, RG int fa){
    RG int x = S[0];
    for(RG int e = fst[u]; e != -1; e = nxt[e]){
        if(to[e] == fa) continue;
        Dfs(to[e], u);
        if(S[0] - x >= b){
            rt[++num] = u;
            while(S[0] != x) bel[S[S[0]--]] = num;
        }
    }
    S[++S[0]] = u;
}

int main(RG int argc, RG char *argv[]){
    n = Read(); b = Read(); Fill(fst, -1);
    for(RG int i = 1, u, v; i < n; i++) u = Read(), v = Read(), Add(u, v), Add(v, u);
    if(n < b){  puts("0"); return 0;  }
    Dfs(1, 0);
    while(S[0]) bel[S[S[0]--]] = num;
    printf("%d
", num);
    for(RG int i = 1; i <= n; i++) printf("%d ", bel[i]);
    printf("
");
    for(RG int i = 1; i <= num; i++) printf("%d ", rt[i]);
    printf("
");
    return 0;
}